The 700T was in Quiet Low power mode and I was using it for web, videos, audio, etc. Normal iPad type of usage. Used both Metro and desktop apps.

Looks like about 6.5-7.5 hours of web usage including audio, video, etc in the low power mode. Hope that helps people who were wondering.

Note: I found during this test, using the 700T as a tablet in your lap, is not the most pleasant experience due to its size and weight. The slick back & rounded edges will not stay put in any position without being held. It really needs a dock or stand, or some sort of case to prop it up on you lap and give it some resistance to moving.

The reason I ask that question is if you really need Low Power Mode to get 7 hours out of battery, though trading off against performance one might as well buy the Ativ Smart PC (non-pro) version? Or am I wrong there?
Is the Low Power mode still more powerful than the Smart PC non-Pro version? And would not using Low Power Mode be of much difference in terms of amount of hours the battery can last?

It's not benchmarking, but for anyone who wants more anecdotal examples, I did another stint with my 700T on battery power.

The power profile was Power Saver, the fan was set to Low, and the screen brightness was at about 60%. Otherwise I didn't try to conserve power by turning off anything else.

I used the tablet steadily, mostly while plugged into the keyboard base, including a lot of YouTube watching, downloading programs & installing them (I didn't let anything restart the computer for the sake of battery testing) and transferring files via USB. So it was often doing two things at once: websurfing & downloading software, transferring files & playing YouTube videos.

I got just over 5.5 hours. I feel it was a pretty good amount, considering the settings and what I was asking it to do.